Gold recovering device and method



June 18, 1935. J. B. GIRAND GOLD RECOVERING DEVICE AND METHOD Filed Feb.9; 1952 2 Sheets-Sheet 1 INVENTOR Umes B. Girm1d, BY W Va ATTORNEYWITNESS 501/ June 18, 1935. J. B. GIRAND GOLD RECOVERING DEVICE ANDMETHOD Filed Feb. 9, 1932 2 Sheets-Sheet 2 INVENTOR @mes .3. GI:

ATTORN EY Patented June 18, 1935 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to a device and method for recovering gold fromother heavy materials such as sand, refuse or gold-bearing ores.

An object of the invention is the provision of a device which utilizesthe centrifugal force developed within a rotating drum to separate theheavy materials from the lighter materials.

Another object of the invention is the provision of a device whichutilizes the centrifugal force developed within a rotating drum for notonly separating the heavy materials from the light -materials, but whichprovides a cushioning bed at the greatest diameter of the rotating drumto re ceive the heavy particles while permitting the lighter particlesto pass beyond the cushioning bed.

A further object of the invention is the provision of a device utilizingthe centrifugal force developed within a rotating drum formed of twotruncated cones having their larger ends connected together andproviding a pocket to receive and retain a cushioning material forcollecting the heavier materials which are thrown out by centrifugalforce from the lighter materials, a spray being included in the drumadjacent the entrance for supplying water streams to loosen, liquefy,agitate and disintegrate the materials entering the drum, the waterbeing supplied in suflicient quantities to carry off the lightermaterials from the drum. I

This invention will be best understood from a consideration of thefollowing detailed description, in view of the accompanying drawingsforming a part of the specification; nevertheless it is to be understoodthat the invention is not con fined to the disclosure, being susceptibleof such changes and modifications which shall define no Figure 5 is atransverse vertical section taken along the line 5-5 of Figure 1,

Figure 6 is a transverse vertical section taken along the line66 ofFigure'l,

Figure 'I is a fragmentary vertical section of 5 a modified form of thedrum shown in Figure 1.

(on. ass-.21)

Referring more particularly to the drawings,

I0 designates a driven shaft to which is secured spaced flanged wheelsII. The flanges of these wheels are at the inner face thereof and areadapted to engage rings I2 secured to the outer Y 5 face of a revolvingdrum, generally designated by the numeral I3. A second pair of wheels Iare mounted upon an axle l5 carried by bearings I6. The axle in adjacentthe front wheel II is mounted on bearings I1 and this bearing, to- 10gether with the bearings I6, adjacent the front wheel I4 is secured toan angle iron beam l8 which is supported upon standards IS. The rearends of the shaft I0 and axle I5 are supported by similar bearings 20secured to an angle iron 15 beam 2|. Thus it will be seen that the fourflanged wheels II and it support the drum I3 while the driven wheels lloperate to revolve said drum. I

A chain 22 trained over a sprocket 23 secured go to the shaft Ill drivessaid sprocket and shaft thro'ugh'a sprocket 24 and a shaft 25 to whichthe sprocket-24 is secured. A hand crank 26 is shown connected to theshaft 25 to provide means for rotating the shaft. It will beappreciated, 5 however, that the shaft 25 may be connected in anyapproved manner with a power plant. Braces 21 support the shaft 25 bythe usual bearings.

The drum I3 is formed of two truncated cones 30 30 and 3| which havetheir ends of greater diam eter connected together at 32, therebyproviding an annular pocket which is V-shaped in cross section and whichis adapted to receive a cushioning element 33 as will be presentlyexplained. 35 It will be noted that the entrance 34 is-of less diameterthan the'discharge opening 35 and is located at a higher horizontalplane than the lower end of the discharge opening 35.

A chute 40 is in communication at its upper 40 end with a hopper 4|which is adapted to receive the gold-bearing sand or ore as indicated at42. A valve, generally designated by the numeral 43, is included withinthe chute 40 and is controlled by a wheel 44 for regulating the quantityof ore 45 or sand passing through the chute 40. The inner lower end 45of the chute projects within the reduced entrance '34 of the drum I3 sothat the materials may be fed into the drum at all times during rotationof the drum.

A pipe 46 is connected with a water supply and a valve (not shown) willcontrol the flow of the water to the perforated discharge pipe 41 whichis located horizontally within the revolving drum I3 and at the reducedportion of the outer end 65 40 fecting a much faster separation thanwhen the of the truncated section of the drum. The perforated dischargepipe 41 is adapted to spray a definite quantity of water onto theincoming gold-bearing sands or ore in order to saturate the ore withsuflicient water to loosen the same so that it will be churned as itenters the drum and suflicient water will be supplied to maintain astream of water through the drum to carry off the lighter materialsafter the heavier metallic materials have been received by the annularcushion.

A travelling carrier in the form of a belt is shown at 50 and is trainedover a, cylinder 5| which acts as an idler for supporting the belt 50just beneath the discharge opening 35. It will be appreciated that adriving drum (not shown) is employed for operating the travellingcarrier 50.

In Figure 7 a modified form of the drum l3 shown in Fig. 6 is disclosedherewith. This type of drum is formed of the truncated sections 52 and53 and is similar in all respects to the drum l3 except that the portion54 is somewhat fiattened to form substantially a ring 55 instead of thesharp pointed member 32, as shown in Fig. 1.

.great deal of gold is found in the sands or ore.

The operation of my device is as follows: Any type of means may beemployed for driving the shaft 25 and likewise .rotating the drum l3. Itis essential, however, that the speed of the drum be under accuratecontrol since the successful operation of the device depends upon thecritical speed of rotation of the drum.

The separation of this machine is effected by utilizing the centrifugalforce within the drum to increase the diflerence in weights between theheavy material and the light material, thus efforce of gravity alone isused. An important feature in this method of separation is effected bythe centrifugal force.

The drumhas its longitudinal axis located in a horizontal plane so thatwhen a particle is rotating about said axis and on a fixed radius thereis a critical speed above which the centrifugal force is greater thanthe force of gravity and the particles will cling to the drum. Belowthis critical. speed the particle will be controlled in its movement bygravity. The critical speed and radius may be deduced from the formula 1inn/E when n= the speed in revolutions per second.

R= the critical radius in feet and it will be noted that R in Figs. 3 to5, inclusive, which represents the various radii discloses the criticalradii of the various sections.

It will be obvious from the above that the cushioning material issubjected to rapid altemations of forces keeping the cushions soft andpreventing packing. These alternating forces are the centrifugal forcewhich tends to throw the particles away from the center and the force ofgravity which tends to pull all of the particles downwardly. As has beenexplained, the net force on particles which are moving through the upperportions of the circular layer is less than the net force on the lowerportions where both cento act on the particles in one direction.

During the operation of the-machine the drum is revolved at the crificalspeed. Sand and other material is admitted to the drum until theperiphery or V-shaped section, indicated at a, in Figure 1, is filled tothe critical radius R, thus forming the controlling cushion. when it isfilled exactly to the critical radius all the mate rial beyond thecritical radius will cling to the V-shaped section 53 but all materialat the radius R will be in unstable equilibrium; that is, just on theborder line between clinging and falling. Since water is being admittedthrough the perforated pipe" the controlling surface is very soft andspongy so that when a particle of material heavier than sand forming thecontrolling cushion touches the surface it will readily and rapidlypenetrate into the controlling cushion. The water which is admitted notonly aids in the' rapidity in the penetration of the heavier particlesbut maintains the contents of the cushion as fluid as far as possible,thus preventing undue packing of the cushion.

After the controlling cushion is in place and ready for operation, thegold-bearing sand or other material will be continuously fed from thehopper ll through a chute 4. and controlled by the valve 43. As thismaterial passes into the drum it is agitated, washed and broken up bythe jets of water adjacent the entrance 34. Since the radius of thatportion of the drum which is adjacent the entrance is less than thecritical radius the material will be churned and agitated after itenters the wider portions of the drum. The specific gravity of thematerial which is fed into the drum is substantially the same as that ofthe collecting cushion. None of this material can force its way into thecontrolling cushion. However, when particles of gold come in contactwith this cushion it penetrates the spongy mass and as the goldparticles pass beyond the surface of the controlling cushion the radiusof its base is increased and thereby centrifugal force is likewiseincreased, thereby overcoming the gravitational pull. The gold will thuscling and remain. within the collecting cushion.

The discharge end of the drum has a greater diameter than the inlet andthe material rapidly works its way to the outlet where it is dischargedafter having been divested of all its metallic contents. This operationis continuous and the heavier material continues to collect until allthe absorbing cushion is displaced or the machine has been emptied.

It has been found in practice that it is advantageous to first build upa controlling cushion of some material heavier than the ore to be fedbut much lighter than the gold. A black iron" sand with a specificgravity of approximately 7 has been successfully used. This cushion issufficiently heavy to prevent the larger rocks or boulders becominglodged therein. The larger gravel and boulders which may be introducedpass rapidly through and are readily divested of the metallic contents.

The stony or earthy substance which is associated with the metallic oreis designated as gangue and this gangue may be in the form of sand,pebbles, and other earthy matter as is well known. 5

Where the gold or other materials do not occur in large quantities, themachine may be operated continuously for a day or more after which allthe materials are removed from the interior.

These concentrates may be separated by a smaller' machine in any wellknown manner.

Where the quantity of the heavier materials is-large a drum of the typeshown in Fig. 7 is employed so that the heavy materials will becontinuously discharged from the openings 56. Any form of means mayembrace the exterior of the .band or ring 55 to receive the particles ofgold as they are discharged.

It will be obvious that where a critical. speed is maintained so thatthe centrifugal force will retain the gangue in a cushion as indicatedat 33 in Fig. 1 and as is also shown in Figs. 3 to 5, inclusive, thegangue will be subjected to the force of gravity at all times but whenthe cushion reaches the uppermost limit in its annular path in avertical plane, the force of gravity will oppose the centrifugal forceand will tend to remove the cushion at these points. Thus as the cushionpasses its highest point of travel the particles will be loosened due tothe opposing forces and the cushion will be less compact at this time asopposed to the bottom portion of the path of the cushion where gravityand centrifugal force combine to move the particles downwardly.Therefore, the particles of gold under the influence of centrifugalforce will penetrate the cushion more readily during the upper portionof the travel of the cushion.

It will be appreciated that no extraneous metal or matter is required inthis method of concentrating the metallic particles from gangueparticles since the cushion in which the metallic particles are embeddedis formed from the gangue particles which enter with the metallicparticles. It will be further appreciated that as the metallic particlesenter the cushion these metallic particles will displace. gangueparticles continuously.

I claim:

l. A device for recovering metallic particles from materials whichinclude gangue comprising a drum. rotating on a horizontal axis havingan intermediate portion of greater diameter than the remaining portionsand forming an annular pocket, cushioning material consisting of gangueand free metal and being retained in the annular pocket, the cushioningmaterial being subjected to rapid alternations of forces due to thechange in direction of the centrifugal force on the individual particlesthus keeping the cushion soft and preventing packing, said cushioningmaterial being in a plane which is at an angle to the horizontal, meansfor feeding metal bearing material to the drum, means for revolving thedrum at a critical speed so that the cushioning material will beretained in the pocket'and receive and retain the metallic particles inthe cushion, and means for supplying a liquid to the materials being fedto the drum.

2. A method of concentrating metallic particles from gangue particleswhich are lighter than said metallic particles, which consists infeeding said particles through a zone in which said particles are causedto move in spiral paths, said paths initially increasing in diameterfrom the inlet end of said zone and then decreasing in diameter towardsthe outlet end of said zone, so that said particles are subjected to avarying centrifugal force in said zone, said centrifugal force beingsufficient only to maintain a layer of gangue in the widest portion ofsaid zone, said centrifugal force being insuflicient to maintain a layerof said gangue adjacent said inlet end and said outlet end, continuouslyfeeding gangue through the zone and causing the particles of the gangueto said metallic particles, which consists in feeding.

said particles through a zone in which said particles are caused to movein spiral paths, said paths initially increasing in diameter from theinlet end of said zone and then decreasing in diameter towards theoutlet end of said zone, so that said particles are subjected to avarying centrifugal force in said zone, said centrifugal force beingsufficient only to maintain a layer of gangue in the widest portion ofsaid zone, said centrifugal force being insuflicient to maintain a layerof said gangue adjacent said inlet end and said outlet end, continuouslyfeeding gangue through the zone and causing the particles of the gangueto move through the spiral path and over the layer of gangue, whilecausing the metallic particles in free metallic condition to penetratesaid layer, the centrifugal force being suflicient to maintain saidmetallic particles in said gangue layer, while moistening said gangueparticles so as to facilitate the penetration of said gangue layer bysaid metallic particles, said gangue layer being maintained in the formof a coherent mass by said centrifugal force.

4. A method of concentrating metallic particles from gangue whichcomprises feeding the gangue and metallic particles into a zone andcausing all of the particles to move through a spiral path whilegradually increasing the diameters of the path to a maximum, forming atthe path of maximum diameter a layer of gangue where the metallicparticles will be collected, said layer being in a plane which is at anangle to the horizontal, revolving the annular layer at a critical speedto maintain a predetermined thickness of the layer while subjecting thelayer periodically to the opposing force of gravity so that the innerportions of the layer will be'loose to permit the metallic particles topenetrate the layer, continuously feeding the gangue containing metallicparticles to the zone and moving the gangue and particles through thesame spiral path so that the metallic particles when reaching the layerwill penetrate the same'while the lighter gangue particles will passover the layer and be discharged from the zone.

5. A method of concentrating mineral particles from gangue particleswhich are lighter than said mineral particles, which consists in feedingthe particles through a zone in which said particles are caused to movein paths, said paths being in planes at an angle to the horizontal andinitially increasing in diameter from the inlet end of said zone to apart in said zone where sufficient particles are interrupted in theirprogress to form a layer of gangue particles which includes free mineralparticles and where centrifugal force will be sufficient to maintainsaid layer substantially intact against the force of gravity, feedingadditional gangue materials containing mineral particles to the pathsand causing said materials to pass over the layer of gangue .whilecausing the mineral particles in free condition to penetrate said layer.I

6. A method of concentrating mineral particles from an aggregate, saidmethod comprising feeding the aggregate and its suspended mineralparticles into a zone of separation in which said the horizontal,interrupting the paths of enough of the aggregate by an unyieldingsurface which defines said zone to accumulate a substantially internallycylindrically-surfaced annularcushion relatively sparse in recoverablemineral particles, said cushion when passing through the highest portionof its path being less compact than when passing through the lowermostportion of its path, flowing a stream of additional aggregate also withsuspended mineral particles across the cylindrical surface of saidcushion, and supplying moisture to said stream at its point of en.-trance into said zone first to agitate and liquefy the stream so as tofacilitate the gravitation of its mineral particles away from their pathof progress across the cushion, second to liquefy the cushionso thatwhen the gravitated particles touch the surface thereof they aredisassociated in free condition from the stream and are caused to'centrifugally penetrate the cushion.

JALIES B. GIRAND.

